Population health: modest glycaemic improvements in a pregnant cohort with mild glucose intolerance decreased adverse outcomes.

BACKGROUND: Adverse perinatal outcomes are common with pregnancy-related mild glucose intolerance. The perinatal impact of improving this population's health, instead of individual health, has not been quantified.

METHODS: We estimated this impact among women with mild glucose intolerance, delivered at The University of North Carolina Women's Hospital from April 1996 to May 2010. We compared observed with predicted risks of perinatal outcomes after simulating a cohort with a one standard deviation decrease in each glucose value. We estimated absolute and adjusted risks, relative risks, and risk differences with Poisson regression and bootstrapped 95% confidence intervals [CI].

RESULTS: Among 3217 women, mean (SD) 1-h screening result was 157 (16) mg/dL; 3-h diagnostic results were 81 (10), 154 (28), 130 (25), and 104 (26) mg/dL for fasting, 1-h, 2-h, and 3-h, respectively. Compared with observed, predicted risks decreased for preeclampsia (9.1% vs. 6.6%, risk ratio [RR] 0.73 [95% CI 0.60, 0.88]), caesarean delivery (30.1% vs. 26.4%, RR 0.88 [95% CI 0.81, 0.96]), preterm birth (13.0% vs. 9.8%, RR 0.75 [95% CI 0.64, 0.87]), birthweight >4000 g (13.4% vs. 10.5%, RR 0.78 [95% CI 0.67, 0.90]), and shoulder dystocia (3.5% vs. 2.2%, RR 0.61 [95% CI 0.46, 0.83]).

CONCLUSIONS: Modestly improved population distribution of glucose tolerance in pregnancies affected by mild glucose intolerance translated to meaningful improvements in perinatal outcomes.